A two-stroke internal combustion engine is disclosed in British Patent 723,972 wherein the injection jet is directed against the incoming combustion air in order to obtain a good preparation of the mixture. The overflow channels lie closely to the exhaust so that the preparation of the mixture takes place in a zone next to the exhaust. Accordingly, the condition must be accepted that a considerable portion of the prepared mixture reaches the exhaust uncombusted and therefore is lost. In this way, the quality of the exhaust gas is also affected so that the environment is burdened with a high charge of toxic material. An inadequate charge of the combustion chamber was determined especially at high rotational speeds whereby power losses occur.
European patent publication 0,302,045 discloses that the fuel is to be injected into the overflow channel already in advance of opening the same for obtaining an adequate preparation of the mixture especially at high engine speeds so that the fuel can prevaporize. Although a good preparation of the mixture is assured in this way, a portion of the mixture is lost because of scavenging losses. For this reason, additional overflow channels, which supply only combustion air, are disposed forward of the overflow channels which supply the air/fuel mixture. The complexity for a two-stroke engine of this kind is, however, very great.